Retrospective analysis of a VACM (vacuum-assisted closure and mesh-mediated fascial traction) treatment manual for temporary abdominal wall closure – results of 58 consecutive patients

Introduction: The optimal treatment concept for temporary abdominal closure (TAC) in critically ill visceral surgery patients with open abdomen (OA) continues to be unclear. The VACM (vacuum-assisted closure and mesh-mediated fascial traction) therapy seems to permit higher delayed primary fascial closure rates (FCR) than other TAC procedures. Material and methods: Patients of our clinic (n=58) who were treated by application of a VAC/VACM treatment manual in the period from 2005 to 2008 were retrospectively analysed. Results: The overall FCR of all patients was 48.3% (95% confidence interval: 34.95–61.78). An FCR of 61.3% was achieved in patients who had a vicryl mesh implanted at the fascial level (VACM therapy) in the course of treatment. Mortality among patients treated with VACM therapy was 45.2% (95% CI: 27.32–63.97). Conclusions: The results of our own study confirm the results of previous studies which showed an acceptable FCR among non-trauma patients who were treated with VACM therapy. VACM therapy currently appears to be the treatment regime of choice for patients with OA requiring TAC.


Introduction
Severe intraabdominal infections with peritonitis, bowel obstruction, pancreatitis, abdominal compartment syndrome and planned second-look surgery are indications for open abdomen (OA) management with temporary abdominal closure (TAC). Various techniques can be applied for TAC management of critically ill visceral surgery patients [1], [2], [3]. Meanwhile, in particular treatment concepts that are based on the principle of negative pressure generation (negative pressure wound therapy, NPWT) have become established, such as VAC or VACM therapy [4]. NPWT can be used to drain off intraabdominal secretions and it has a positive effect on the treatment of abdominal compartment syndrome [5]. It seems that high FCRs can be achieved by application of VACM therapy, which is based on the principle of mesh-mediated fascial traction [6], [7]. Patients with TAC may develop enteroatmospheric fistulas (EAF), which constitute a complication that is difficult to treat. Reported fistula rates during application of NPWT are 21% [8]. However, a causal connection between the occurrence of EAF and NPWT in open abdomen is questionable [9], [10]. Due to insufficient evidence, the optimal therapy for open abdomen continues to be unclear [11], [12]. In Germany, a multicentric laparostoma register of the German Society for General and Visceral Surgery (DGAV) has been established as a contribution to improving the data available on treatment of the open abdomen in order to be able to derive evidence-based therapy recommendations from these data in future [13]. As a result, the major objectives in the treatment of patients with OA are as follows: achieving fascial closure in the course of treatment and avoiding the occurrence of EAF [14]. Various studies showed that VACM therapy was associated with higher FCRs and lower incidence of EAF during treatment than VAC therapy alone [15], [16], [17]. In this retrospective study, the FCR, the mortality rate and the incidence of enteroatmospheric fistulas among patients of our department who were treated using a combined VAC/VACM treatment manual were to be retrospectively analysed.

Data collection and statistical analysis
This study retrospectively covers all patients of our department who underwent open abdomen management with TAC for conditions of non-traumatic origin in the period from 2005 to 2008 (n=58). The following patient charac-teristics and therapy results were analysed: age, sex, indication for open abdomen treatment, severity of disease at the beginning of treatment with TAC, using the Simplified Acute Physiology Score (SAPS II), SAPS II for survivors and non-survivors, length of stay (LOS), FCR, mortality rate and EAF rate during treatment. After establishing a TAC in the intensive care unit, the SAPS-II was determined as described by Le Gall et al. [18]. The mean value, standard deviation, median and 95% confidence interval were considered in the data given. The analysis was conducted using SPSS Version 16.0. The level of significance was set at p≤0.05.

Treatment manual
All patients were treated using a combined VAC/VACM therapy in accordance with a specified treatment manual ( Figure 1). Since there was an indication for TAC, a primary commercial V.A.C. ® Abdominal-Dressing TM (Kinetic Concepts Inc., USA) was applied. Planned surgical revisions were subsequently performed every 48 hours. In patients with clean intraabdominal conditions, the fascia was closed during the first surgical revision (second-look surgery). Where fascial closure could not be accomplished at that time, the Abdominal-Dressin TM was changed. Where fascial closure could still not be achieved during the second surgical revision after application of the VAC dressing, polyglactin mesh (Ethicon, Germany) was sutured as inlay between the fascial edges (VACM) to prevent further retraction of the fascial edges. During the subsequent surgical revisions, intraabdominal access was achieved by incision of the polyglactin mesh along the median line to leave the fascial edges intact. At the end of surgery, the polyglactin mesh was closed by an overlapping suture along the median line in order to approximate the fascial edges and thus to reduce the laparostoma.

Results
Age and sex 39.7% of all patients were female and 60.3% were male. The average age of all patients was 67.4 ± 15.7 years (median: 68.5 years). With an average age of 74.6 ± 12.7 years (median: 80.0 years), the female patients were significantly older than the male patients with an average age of 62.7 ± 15.9 years (median: 65.0 years) (p=0.005).

Discussion
The patients who underwent VACM therapy in our department had a high mortality rate of 45.2%. However, the relevant literature also indicates mortality rates >30% for patients with open abdomen and TAC [2], in individual cases mortality rates >50% have been described [19]. Mortality is particularly high in patient groups with secondary peritonitis: in a prospective study by Fortelny et al. [20] which only included patients with a septic intraabdominal focus it was even 55.2%. Since patient age is an important determinant of the outcome, it must also be considered when interpreting the results of treatment: Vogel et al. [21] found that advanced age was associated with significantly higher complication rates and prolonged treatment courses (p<0.001). In 2011, Acosta et al. [22] reported a significant influence of advanced age on mortality in patients with temporary abdominal wall closure (p=0.027). The FCR reported after VACM therapy was 61.25% and thus higher than in studies where VAC therapy was applied alone (33%) [23], but it was lower than in other studies which reported FCRs of 76% [22], 78% [7] and 87% for patients who underwent VACM therapy [16]. In the publication by Willms et al. [16], the average age of the patients was 53 years compared to an average age of 68.5 years of our own patient group. In some cases, the indications for using TAC differ considerably between our own patient group and the populations described in the literature (trauma vs. non-trauma patients). It is known that only relatively low FCRs can be achieved among patients with secondary peritonitis compared to patients without septic intraabdominal foci [15], [24]. Extraabdominal infections in patients who underwent TAC were also associated with a lower FCR [21]. Patients with severe peritonitis often require lengthy treatment, because early fascial closure is usually not possible in such cases. At the same time, it was reported that the chances of fascial closure decrease with increasing duration of treatment [3]. The EAF rate of 6.5% during VACM therapy corresponds to the data described in the literature, although individual authors published fistula rates of 0% for patients who underwent VACM therapy [16]. The severity of disease at the beginning of treatment (SAPS II) is an important prognostic factor. The findings in our patient group show that a high SAPS II is associated with increased mortality. Such a correlation is obvious, but a comparison with the literature is difficult: in some studies intensive medical scores are not indicated regu-larly and sometimes other score systems (APACHE II, ISS) are used [2]. The length of hospital stay (LOS) is significantly prolonged after mesh implantation. The LOS can be significantly reduced by rapid abdominal closure if no relevant complications occur during the course of treatment (p=0.002). The treatment manual used was already described in a similar form in other publications, and even higher FCRs were reported in some of these studies [16], [25]. There are no valid data on the optimum time for performing additional mesh implantation and starting VACM therapy. It is unclear whether even higher FCRs can be achieved in the course of treatment by implanting mesh already during initial establishment of TAC. The validity of our own study is limited by the fact that the patients were not classified according to their respective intraabdominal findings on the basis of uniform standards, as suggested by Björck et al. [26]. Therefore, as in many other studies, the described results cannot easily be transferred to other patient populations. The analysed patients were treated in the period from 2005 to 2008. The materials (Abdominal Dressing TM , KCI, poylglactin mesh) and therapy concepts (VACM) used for these patients are still commonly used. The data presented here can therefore be used to extend current evidence, although new commercial systems, such as ABThera TM (Kinetic Concepts Inc., USA) are meanwhile available for TAC therapy and the first treatment outcomes have been published [27]. Furthermore, the retrospective evaluation of data, the lack of a control group and the single-centre character of the study are limiting factors in the interpretation of results.

Conclusions
VACM therapy should be used whenever possible, especially for non-trauma patients requiring TAC. By using the principle of mesh-mediated fascial traction, it is possible to achieve acceptable fascial closure rates and low rates of enteroatmospheric fistulas during the course of treatment. In future it may be possible to derive evidencebased recommendations for treatment from the laparostoma register of the German Society for General and Visceral Surgery (DGAV).